The research led by University of Miyazaki in southern Japan has revealed that a chemical found in blueberry leaves has shown a strong effect in blocking the replication of the Hepatitis C virus.

Currently, there is no vaccine for HCV, and though a combination drug regimen can clear HCV infection, this treatment is only about 60pct effective on average and poses risks of severe side effects.

Lead researcher Hiroaki Kataoka hypothized that since HCV is localized in the liver and can take 20 years or more to develop into disease, a dietary supplement might help slow or stop disease progression.

During the study, the researchers screened nearly 300 different agricultural products for potential compounds that suppress HCV replication and uncovered a strong candidate in the leaves of rabbit-eye blueberry (native to the southeastern US).

They purified the compound and identified it as proanthocyandin (a polyphenol similar to the beneficial chemicals found in grapes and wine).

While proanthocyandin can be harmful, Kataoka and colleagues noted its effective concentration against HCV was 100 times less than the toxic threshold, and similar chemicals are found in many edible plants, suggesting it should be safe as a dietary supplement.

The researchers are now planning to explore the detailed mechanisms of how this chemical stops HCV replication.